Heat exchanger tube reamer



Aug. 27, 1957 J. c. FULLER HEAT EXCHANGER TUBE REAMER Filed Oct. '7,1955 iaiisiiia .I'NVENTOR JOSEPH C. FULLER WW NW N QN ATTORNEYS UnitedStates Patent HEAT EXCHANGER TUBE REAMER Joseph C. Fuller, RedondoBeach, Calif., assignor, by

mesne assignments, to California Research Corporation, San Francisco,Calif., a corporation of Delaware Application October 7, 1955, SerialNo. 539,105

1 Claim. (Cl. 15--104.1)

This invention relates to tube cleaning apparatus, and more particularlyto tube cleaning apparatus for removing deposits and other accumulationsof foreign matter from the interior surfaces of the tubes of boilers,condensers and other heat exchangers; and an object of this invention isto provide tube cleaning apparatus the cleaning shaft of which isautomatically extendible and retractable with respect to the body ofsaid apparatus while said shaft is simultaneously rotating.

Deposits, incrustations and other accumulations on the inner walls ofheat exchanger tubes create well-known problems in the operation of heatexchanger apparatus, including the problem of reduced heat transferefficiency. The magnitude of each problem created varies with manyfactors, including the time the heat exchanger apparatus is in service,the composition of the cooling medium being circulated through the heatexchanger tubes and the tube diameters. In most cases one or more ofthese factors eventually necessitates heat exchanger apparatus tubecleaning to prevent the necessity for tube replacement and to maintain aproper heat transfer rate for the heat exchanger apparatus.

Heretofore the cleaning shafts of tube cleaning apparatus have beengradually advanced by hand into the tubes to be cleaned as the rotaryaction of the cleaning shafts have removed incrustations. This procedurehas necessitated hand movement of all or a substantial por tion of thetube cleaning apparatus substantially continuously during the entirecleaning operation on the tubes of a heat exchanger. Such hand movementoperations become particularly tiring and tedious on large multitubedheat exchanger equipment. An object of this invention is to provide tubecleaning apparatus all except the cleaning shaft of which remainsstationary with respect to the heat exchanger during cleaning of aparticular tube, and which does not require the cleaning shaft to beadvanced by hand into the tubes to be cleaned.

The foregoing objects and others ancillary thereto I prefer toaccomplish as follows: According to one preferred embodiment of myinvention, I provide in combination with a main body portion adapted tobe positioned near tubes to be cleaned, a cleaning shaft coaxial withsaid main body portion, said shaft having cleaning means supported onone end thereof, means for rotating said shaft, and means foralternately extending and retracting said shaft with respect to saidmain body portion while said shaft is simultaneously rotating.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claim. The invention willbe better understood, however, both as to organization and method ofoperation, and further objects and advantages of the invention will .beapparent, from the following detailed description of a 2,303,842Patented Aug. 27, 1957 ice preferred embodiment of the invention whenread in connection with the accompanying drawing in which the samereference numbers are used to illustrate similar parts in the variousfigures and in which:

Fig. 1 is a combination longitudinal vertical section and elevation viewof an embodiment of the invention and of associated heat exchangertubes, showing a longitudinal section of the cylinder, piston andcleaning shaft;

Fig. 2 is an enlarged vertical sectional view of that portion of theembodiment of Fig. 1 where the driving force is applied to the cleaningshaft to rotate that shaft;

Fig. 3 is a combination end elevation and sectional view taken alongline 3-3 in Fig. 2;

Fig. 4 is a vertical sectional view of the piston, showing the detailsthereof and the connection of the cleaning shaft thereto.

Referring now to Fig. 1, square cleaning shaft 1, which may be, forexample, steel, is rotatably attached to piston 2 and rotatablysupported in plates 3 and 4, and reciprocates in cylinder 5 underpressure alternately from fluid in pipes 6 and 7, respectively, whileshaft 1 is simultaneously rotated by low-speed motor 8 through drivingmeans 9, which may be, for example, a V-belt.

In more detail and still referring to Fig. 1, the entire tube cleanerassembly shown is first positioned in relation to heat exchanger tubes10, for example, by being supported on holders 11 from an overheadtrolley, so that simultaneous extension and rotation of cleaning shaft 1will cause cutting tip 12 to dislodge deposits and other accumulationsof foreign matter from the interior Walls of tubes 10.

Still referring to Fig. l, the elements, together with their co-action,through which rotational motion is imparted to shaft 1 from motor 8, areas follows: Plate .3 and cylinder 5, both of which may be steel, aresecured together, for example, by welding. Motor 8 also may be securedto cylinder 5, for example, by straps 13 and bolts 14 as shown or,alternatively, motor 8 may be located remote from the body of thecleaning apparatus and may drive shaft 19 through a flexible connection.Plates 15, 16 and 17, which may be steel and which may be, for example,bolted as shown, serve to prevent relative motion among plates 3, 4 and18. Plates 4 and 18 may also be steel. late 17 maybe extended as shownto provide further support for motor 8. Upon rotation of motor 8, whichmay be for example, an electric motor or an air motor, power istransmitted through shaft 19 to a conventional outboard bearing 20 whichis secured to shaft 19 and rotatably supported in plates 3 and 18. Frombearing 20 power is transmitted through pulley 21, which is secured tobearing 20, and through driving means 9 and pulley 22 to bearing 23, towhich pulley 22 is secured. Bearing 23 is rotatably supported in plates3 and 4 in a manner similar to the support of bearing 20 in plates 3 and18. However, bearing 23 differs from bearing 20 in that, While bearing20 is secured to shaft 19, bearing 23 is not secured to shaft 1 butpermits longitudinal movement of shaft 1 therethrough. Square shaft 1 iskeyed to bearing 23 through a square longitudinal hole 36 in bearing 23which permits the aforementioned longitudinal motion, but which alsoprevents relative rotational motion between shaft 1 and bearing 23. Thepower received by hearing -tively that piston 2 is at the end of itsworking stroke. desired, a similar gage can be installed near theotherend 24A of which is secured to shaft 1 and the outer portion 243 ofwhich is secured to piston 2.

Still referring to Fig. l, the elements, together with their co-action,through which reciprocating motion is imparted to shaft 1, are asfollows: With valve handle 25 of fourway valve 26 in the position shownby solid lines, with pipe 27 connected to a source of fluid underpressure, for example air, and with piston 2 in the position shown bysolid lines, the fluid will travel through pipe 6 into cylinder and willexert a pressure over the effective area --of surface 28 of piston 2.The fluid will also travel through hole 42 in piston 2, through hollowshaft 1, and out of the cleaning end of shaft 1 past cutting tip 12, toexert a flushing action in the region of cutting tip 12 to aid inremoving accumulations dislodged by cutting tip 12. At the same time,the pressure over the effective area of surface 29 of piston 2 will beapproximately atmospheric, because a pathway is provided to theatmosphere from surface 29 of piston 2 through pipe 7, valve 26 and pipe30. Therefore, the differential pressure between surfaces 28 and 29 ofpiston 2 will force piston 2 to the position shown by dotted lines.Desirably, the fluid pressure in pipe 27 should be such that there willbe available the maximum differential pressure needed between pistonsurfaces 28 and 29 to force piston 2 down cylinder 5 at a speedcommensurate with the cutting efficiency of rotating cutting tip 12 inany given heat exchanger tube. The pressure necessary in pipe 27 whichmay, for example, lie in the range 50-100 p. s. i. g., will depend upona number of factors, for example, the relative dimensions of the variousparts of the present apparatus, coefficients of friction present, thecondition and efliciency of cutting tip 12, and the sizes and conditionsof the heat exchanger tubes to be cleaned. However, for a givenapparatus to be used to clean given heat exchanger tubes, the necessarypressure may be calculated by conventional mathematical methods, or itmay be determined by a few actual test runs. In any event, desirably,valve 26 should be so selected so that if necessary it may bemanipulated to reduce its output pressure from the pressure in pipe 27,or alternatively, an additional valve should be used in pipe 27 for thispurpose.

When piston 2 has travelled to the position shown by dotted lines, itwill be at the end of its working stroke, and will be stopped byresilient annular bumper 31, which may be, for example, rubber ofsufficient stiffness so that it will not collapse under impact of piston2 and will satisfactorily absorb the shock of the impact.

Manual movement of the handle 25 of valve 26 to the position shown bydotted lines after piston 2 has reached the end of its working strokeand is in the position shown by dotted lines will cause the fluid underpressure in pipe 27 to travel through valve 26, pipe 7, and throughopen-- ing 32 in bumper 31 to surface 29 of piston 2. The pressure onsurface 29 of piston 2 will thereupon force piston to return downcylinder 5 on its withdrawal stroke, against the atmospheric pressure onsurface 28 of piston 2, to annular resilient bumper 33. Bumper 33 isconstructed of the same material as bumper 31 but need not have anopening therein corresponding to opening 32 in bumper 31.

Pressure gage 34, responsive to pressure in cylinder 5, serves toindicate when piston 2 has reached the end of its working stroke, sothat the operator may be certain when to throw handle 25 of valve 26 tothe position shown by dotted lines, and thus to start piston 2 on itswithdrawal stroke. During the working stroke of piston 2, the pressuresensitive elements of pressure gage 34 communicate with the atmosphere,and thus gage 34 reads zero gage pressure. When surface 28 of piston 2passes entrance 35 of gage 34 on the working stroke of piston 2, gage 34will immediately register the pressure at surface 28 of piston 2, andthe operator will then know posi- 4 of the apparatus to indicate whenpiston 2 has reached the end of its withdrawal stroke.

Referring now to Fig. 2, the details of construction of bearing 23 andits interaction with shaft 1 are as follows: Bearing 23, which may bebrass, has a square longitudinal hole 36 therethrough into which squareshaft 1 closely fits in a manner that allows reciprocating motion ofshaft 1 through bearing '23 and that prevents relative rotational motionbetween shaft 1 and bearing 23. Gland nut 37, threadedly connected intobearing 23, and having therethrough round hole 38, of greater diameterthan the diagonal diameter of shaft 1, compresses packing 39 closelyagainst all four sides of shaft 1. Shaft 1 and bearing 23 are thussealed together to prevent pressure from escaping from cylinder 5through bearing 23. Packing 39 may be of any suitable material that willbe reasonably resistant to the frictional effects from shaft 1 whilefurnishing an effective seal, for example an interwoven composition ofasbestos fibre and brass wire.

Referring now to Fig. 3, the'combination end elevation and sectionalview there shown indicates square shaft 1 keyed into square hole 36 ofbearing 23, and also indicates the cross-sectionalrelationship betweengland nut 37 and shaft 1. It will be apparent to those skilled in theart thatshaft 1 may be keyed to hearing 23 in a variety of ways otherthan making shaft 1 square and keying into a square hole in bearing 23.

Referring now to Fig. 4, the details of construction of double-actingpiston 2 and its interaction with cylinder 5 and shaft 1 are as follows:Piston 2 is constructed in two threadably connected parts, 2A and 2B,that screw together to hold the outer portion 24B of bearing race 24securely. Inner portion 24A of bearing race 24 is se cured to shaft 1 ina manner that will prevent any relative movement between portion 24A andshaft 1. For this purpose, the cross-section of those portions of shaft1 that lie within piston 2 may be round to correspond with the roundhole in bearing race 24. A nut 40 may be threadably attached to shaft 1as shown to aid in holding portion 24A of bearing race 24 in place.Annular sealing rings 41 which may be, for example, rubber, serve toprevent the combination motive and flushing fluid from seeking a pathwaybetween piston 2'and cylinder 5.

From the foregoing description it may be seen that the presentinventionoperates simply and in a highly effective and novel manner to effectadvancement of a heat exchanger tube reaming shaft into theheat-exchanger tubes to be cleaned, without laborious hand effort. Itmay be also seen that the novel design utilizes only one fluid for bothmotive power for reciprocating the reaming shaft and .for flushingdebris from the shaft cutting tip and adjacent areas.

As previously mentioned, the automatic pressure gage feature of theinvention enables the operator to determine instantly when the cleaningshaft has arrived at the end of its working stroke, so that he maythereupon manipulate the operating fluid four-way valve, toautomatically retract the cleaning shaft from a heat exchanger tube.

It is also important to note that with the line pressureof the air orother combination motive and cleaning fluid selected and adjusted sothat the cleaning shaft on its working stroke will advance the cuttingtip at a speed commensurate with the cutting tip efliciency, the samepressure will cause the withdrawal stroke to be made at a greater speed,primarily because of the reduced resistance to shaft withdrawal that isoffered by the cleaned heat exchanger tube. This inherent feature speedsup and improves the over-all efficiency of tube cleaning operations.

Although only preferred arrangements and modes of construction andoperation have been illustrated and described, those skilled in the artwill be able to perceive numerous modifications, variationsand changesin this in vention that could be made without departing from the spiritthereof. All such modifications, variations and changes that could bemade in the arrangements and modes described herein that fall Within thescope of the appended claim are intended to be embraced thereby.

I claim:

In a tube cleaning device having a cylinder, a coaxial shaft sealedtherein, a piston slidably supported in said cylinder, said shaft havingan inner end rotatably connected to said piston, the outer end of saidshaft projecting out of said cylinder and provided with a tube cleaningmeans, and means for rotating said shaft; the combination comprisingmeans for connecting the ends of said cylinder alternately to a sourceof pressure fluid and to the atmos phere to extend and to retract saidshaft and said cleaning means, and pressure responsive meanscommunicating with a port in said cylinder adjacent its outer end andadapted to be alternately connected to said pressure fluid source and toatmosphere by the traverse of said piston 3 across said port, saidpressure responsive means thereby indicating the extended position ofsaid piston and said shaft.

References Cited in the file of this patent UNITED STATES PATENTS261,978 Allison Aug. 1, 1882 513,947 Lincoln Jan; 30, 1894 592,953Robeson et a1. May 18, 1897 677,112 Crarnei June 25, 1901 1,109,533Keith Sept. 1; 1914 1,475,989 Eastc'rday Dec. 4; 1923 2,380,098 DoernerJuly 10, 1945 FOREIGN PATENTS 437,784 Italy July 12, 1948

